Abstract/Summary

Ancient rockshore deposits are the rarest sedimentary rocks on Earth. Less than 200 examples span the planet’s entire history, but they preserve important records of past environments, including sea-level changes and
unusual fossil communities. The most celebrated example, dating from the earliest Jurassic, is found at Ogmore-by-Sea in South Wales. This article describes the history of environmental change at Ogmore, and why these rocks can help us to interpret the deposits of ancient rocky shores worldwide.